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Passive Leg Raising (PLR) — Dynamic Fluid-Responsiveness Test

Gold-standard dynamic test that predicts fluid responsiveness at the bedside by using a 300-450 mL autologous fluid challenge and measuring changes in cardiac output.

Written by: Saygı Hospital Health Guide Editorial Board
Published: · Last updated:

This content is for general information; please consult your physician for diagnosis and treatment.

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What is Passive Leg Raising (PLR) — Dynamic Fluid-Responsiveness Test?

Passive Leg Raising (PLR) is a reversible autologous fluid-loading test used to evaluate fluid responsiveness. Raising the legs to 45° transfers roughly 300-450 mL of blood from the lower-limb and splanchnic veins into the central circulation, producing a hemodynamic effect equivalent to a small IV fluid bolus.

An increase of 10-15% in cardiac output (CO) or a surrogate (VTI, stroke volume, arterial pulse contour) after PLR is considered a positive response (preload responsive). Sensitivity ~85%, specificity ~91% (Monnet 2016 meta-analysis).

PLR's key advantage is reversibility — if the patient is not fluid responsive, the legs are lowered and unnecessary fluid loading is avoided. This property is critical in ARDS, cardiac dysfunction, and septic shock.

Unlike other dynamic tests (SVV, PPV, IVC collapse), PLR remains valid in spontaneously breathing patients, those with arrhythmia, and during low-tidal-volume ventilation. It is therefore preferred in patients with limitations that compromise mechanical-ventilation-based tests.

Symptoms

Shock states (septic, hypovolemic, cardiogenic) — evaluation of responsiveness before fluid therapy
High vasopressor requirement — to determine whether additional fluid will provide benefit
Oliguria and risk of renal failure — expectation of improved renal perfusion with fluid loading
ARDS where fluid balance is critical — to avoid excessive fluids, responsiveness should be tested first
Cardiogenic shock — assessment of preload reserve while reducing risk of pulmonary edema

Risk Factors

Intra-abdominal hypertension (IAH/ACS) — abdominal pressure >12 mmHg reduces test sensitivity
Lower-extremity DVT — theoretical risk of thromboembolism (practical clinical risk is low)
Severe pulmonary hypertension — acute right-ventricular loading, RV failure may become evident during PLR
Increased intracranial pressure — PLR may raise ICP (use with caution in head trauma, intracranial hemorrhage)
Quality of the cardiac-output measurement (echocardiographic VTI is operator-dependent; PiCCO/pulse contour is more standardized)

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Before empirical fluid therapy in shock — if PLR is positive, give 500 mL crystalloid
  • In refractory hypotension — evaluate fluid response before escalating vasopressors
  • In patients with cumulative positive fluid balance — is more fluid warranted? Predict with PLR

Treatment Methods

01
Baseline positioning — semi-recumbent (head of bed 45°) with legs flat on the bed
02
Baseline CO / stroke volume / VTI measurement — preferably via continuous monitor (PiCCO, LiDCO, arterial pulse contour) or echocardiography (LVOT VTI)
03
Raise the legs rapidly to 45° (using the bed tilt, not manually, for consistency), lower the head to horizontal, and maintain 60-90 seconds (peak response at 1-2 min)
04
Repeat CO / stroke volume / VTI measurement — compare with baseline; an increase of 10-15% indicates fluid responsiveness
05
Return to baseline position — legs down, head 45°, hemodynamics return to normal within 1-2 minutes
06
Positive response → 250-500 mL crystalloid bolus (Ringer's lactate or a balanced solution such as Plasmalyte). Negative response → withhold fluid, escalate vasopressor, or add inotrope (after RV/LV evaluation by echocardiography)

Which Department to Visit?

You can visit our Kardiyoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.